1. Field of the Invention
The present invention relates to user interfaces for computer display systems. Specifically, the present invention relates to the direct manipulation of text on a computer display screen.
2. Prior Art
Modern interactive computer systems have become very popular for use in word processing. With the development of more powerful and faster computer hardware, these state-of-the-art computers are capable of processing greater amounts of data in a shorter amount of time. Similarly, ever more sophisticated and powerful software systems are being developed to run on these high powered computers. Specifically, word processing software has become a common component in most any computer system. A goal in the design and development of these word processing software applications has been to design the most powerful system possible while maintaining an understandable and easy-to-use user interface.
Word processing software user interfaces employing a "what you see is what you get" (i.e. WYSIWYG) philosophy have gained a great deal of popularity among computer users. One reason for this popularity is that users prefer to see a visual result of the functions and operations they apply to a particular document or text region of the display screen. This visual reinforcement is an important aspect of any software package assisting a user in generating or manipulating text. Often, a user is not sure exactly what result to expect from the application of a particular command or operation; yet knowing the exact form of the results is important in determining whether or not the operation should be performed at all.
Prior art computer systems employ various methods for implementing user interfaces with a WYSIWYG philosophy. Specifically, several systems provide commands for cutting (i.e. removing), copying, and pasting (i.e. inserting) blocks of text in a computer system environment or a particular document using a highly visual and manipulable user interface methodology. Two examples of such prior art systems are the Finder.TM. interface of the Apple Macintosh.TM. computer, developed by Apple Computer, Inc. of Cupertino, Calif. and Microsoft Word.TM., developed by Microsoft., Inc. of Redmond, Wash. Both these and other computer-based systems employ a text manipulation technique whereby a block of text is first identified for manipulation using a series of keyboard keystrokes or using a cursor control device for positioning a cursor (i.e. pointer) symbol on the display screen. A computer mouse or trackball device may be used as a cursor control device. The identified (i.e. selected) block of text is typically indicated on the display screen in a contrasting color or reverse video.
Once selected, various operations may be applied to the selected block of text in these prior art systems. Two such operations most commonly used are: (1) the cut or remove operation and (2) the copy operation. When the cut operation is invoked, the selected block of text is typically deleted from the display screen and the remaining unselected portions of text from the text region or document are reformatted to fill the blank area left by the deleted block of text. In addition to being removed from the display screen, the deleted text is typically transferred to a memory buffer or temporary disk file neither of which is visible to the user on the display screen. In the Apple Macintosh.TM. computer, this temporary buffer is called a clipboard or clipboard file. Other systems may use a different terminology; but, a temporary storage buffer not visible to the user typically exists in these systems.
When the copy operation is invoked for a selected block of text, the selected block of text is copied to the clipboard, but remains in position within the document. Thus, an invisible copy of the selected text is maintained within the clipboard or temporary holding buffer in a manner similar to the cut operation.
Other derivative forms of the cut and copy operations may exist in the prior art, but the steps described above generally apply to the prior art systems. For example, a block of text may first be selected. The user may then choose to insert new text into the position occupied by the selected text. If the user begins to insert new text by typing characters on a keyboard coupled to the computer system, prior art systems typically perform an implied cut or remove text operation on the selected text prior to insertion of the new text. This implied cut operates in the same manner as the cut operation described above. That is, the selected block of text is removed from the display screen and transferred to the invisible clipboard.
In addition to cut and copy operations, prior art systems typically provide a means for pasting (i.e. inserting) previously cut or copied text into a new position within a document or a text region on the display screen. The typical prior art pasting operation is performed by first identifying an insertion position within a document or text region where the insertion will be applied. This insertion position identification may be performed using keyboard key strokes or the cursor control device (i.e. mouse). Prior art systems typically indicate the identified insertion position by means of a small visual symbol displayed on the display screen at the paste position. Once this position is identified, the user then invokes a paste or insert command. On invocation of the paste command, the current contents of the clipboard or temporary holding buffer are transferred to the document or text region starting at the insertion position. The other unselected portions of text are reformatted to make room for the newly pasted block of text. The pasted block of text is thus transferred from the invisible clipboard or temporary holding buffer to the indicated insertion position. Once the paste operation is complete, the user is able to view the result of the operation on the display screen. Unfortunately, the user is not given the opportunity to view the block of text in the clipboard prior to the completion of the paste operation. While some prior art systems provide a means for viewing the clipboard or holding buffer, this viewing involves activating a separate set of controls and often may obscure a portion of the display screen while the clipboard is being viewed. In addition, full text formatting of the block of text in the clipboard is lost while viewing the clipboard.
Other prior art systems outside of the computer-based word processing environment are designed for drawing graphics images and text on a computer display screen. One such prior art system is MacDraw.TM. developed by Apple Computer, Inc., Cupertino, Calif. These prior art drawing systems provide a means for inserting and manipulating blocks of text; however, these systems typically treat each block of text as a separate entity or object. Since each text object is separate, the capability to reformat an entire document is lost. For example, one block of text cannot be conveniently merged into another block with the corresponding line justification and word wrap operations being performed as in a word processing environment. In addition, drawing systems often impose size restrictions on the number of characters inserted into a particular text object.
Thus, a means for the direct manipulation of text is needed. It is, therefore, an object of the present invention to provide a means for directly manipulating text in a way that provides effective visual feedback for the user. It is a further object of the present invention to provide a direct text manipulation method requiring fewer user control activations thereby simplifying the user interface. These and other objectives and features of the present invention will be discussed in more detail in the sections that follow.